PSF1 forms tetramer, go-ichi-ni-san (GINS) complex, with SLD5, PSF2 and PSF3 of constitutive protein, which binds to MCM (mini-chromosome maintenance complex) and cell division cycle 45 (cdc45). That is known to be associated with initiation of DNA replication and elongation (non-patent reference 1: Structure of the human GINS complex and its assembly and functional interface in replication initiation. Kamada et al. Nat. Struct. Mol. Biol. 2007; 14:388-396 and non-patent reference 2: The human GINS complex associates with cdc45 and MCM and is essential for DNA replication. Aparicio et al. Nucleic Acid Res. 2009; 37:2087-2095).
With respect to the relation with cancer, the expression of PSF1 is considered to increase in human breast cancer cell. It is also reported that the reduction of the expression of PSF1 had caused the suppression of proliferation significantly. Furthermore, it is reported that overall survival rate among breast cancer patients, of which the PSF1 expression level is low in its cancer tissue, is significantly higher, compared to the patients, of which the level is high (non-patent reference 3: Up-regulation of psf1 promotes the growth of breast cancer cells. Izumi et al. Genes to Cells 2010; 15:1025-1024).
Expression of PSF1 has been documented in the cancer tissue derived from malignant melanoma, lung cancer and esophagus cancer (Non-patent reference 4: Comprehensive expression profiling of tumor cell lines identifies molecular signatures of melanoma progression. Ryu B. et al. ProsOne 2007; 7:e594, Non-patent reference 5: PSF1, a DNA replication factor expressed widely in stem and progenitor cells, drives tumorigenic and metastatic properties. Nagahama Y. et al. Cancer Res. 2010; 70:1215-24, and Patent document 1: International Publication Gazette WO2003/42661). The relation between PSF1 and the cancer stem cell is also known in non-patent reference 5.